Scientists Discover New Trigger for North Atlantic Phytoplankton Bloom to be Eddies, Not Sunlight

Jul 07, 2012 02:59 AM EDT

Scientists at the University of Washington and collaborators discovered that large whirlpools in the ocean, or eddies, triggers the annual growth spurt of phytoplankton in the North Atlantic Ocean.

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Every spring, the water at North Atlantic Ocean burst into color, first “greening” then “whitening”, due to the growth of one plankton species after another, which is known as North Atlantic Bloom. Until recently, longer hours of sunlight were considered to be the cause the bloom. But new study that was published in Science has shown that eddies were the factor.

"Our results show that the bloom starts through eddies, even before the sun begins to warm the ocean," said Amala Mahadevan, the lead author of the research and an oceanographer at the Woods Hole Oceanographic Institution in Mass.

Eddies are formed when cold water from north flows under the warm water from the south. This helps brining plankton to the surface of the ocean.

The study has also emphasized the importance of knowing the timing of the bloom.

"That timing makes a significant difference if you think about the animals that eat the phytoplankton," said Eric D'Asaro at UW, one of the co-authors on the paper.

"If they get the timing wrong, they'll starve," said Craig Lee, another oceanographer who contributed in the research.

The discovery reminded the science circle that ocean is still a mysterious place.

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"Every undergraduate who takes an introductory oceanography course learns about the ecological and climate significance of the North Atlantic Bloom--as well as what causes it," said Don Rice, program director in NSF's Division of Ocean Sciences, which funded the research.

"This study reminds us that, when it comes to the ocean, the things we think we know hold some big surprises."